Portable utility



Nov. 11, 1958 G. w. TAMMEN 2,860,224

PORTABLE UTILITY Filed Oct. 28, 1955 2 Sheets-Sheet 1 I IZc/bczffor GZearz dTodmrnea J6 Cito'rzzeg Nov. 11, 1958 G. w. TAMMEN 2,860,224

PORTABLE UTILITY Filed Oct. 28, 1955 2 Sheets-Sheet 2 I Zz/eziior 6 @012, 6d Tam-2026a ym b 2,850,224 Patented Nov. 11, 1958 United States Patent Ofiice PORTABLE UTILITY Glenn W. Tammen, Park Ridge, Ill., assignor to St. Joe Machines, Inc., St. Joseph, Mich., a corporation of Michigan Application October 28, 1955, Serial No. 543,325

19 Claims. (Cl. 219-19) My invention relates to portable utility devices, and includes among its objects and advantages increased adaptability in folding different parts of a foldable device together.

When embodied in a portable electric heater, it also provides improved protection against heat injury to furniture.

In the accompanying drawings:

Figure 1 is a plan view of a heater according to the invention in closed condition;

Figure 2 is a perspective of the same closed heater standing on end;

Figure 3 is-a plan view of the heater opened up for use with both shells in the same plane;

Figure 4 is an enlarged section on line 44 of Figure 3;

Figure 5 is an enlarged plan view of the supporting shell in the position of Figures 3 and 6;

Figure 6 is an edge elevation of the complete heater in the position of Figure 3; and

Figure 7 is an edge elevation of the heater in position for use with the covering shell for a plinth.

In the embodiment selected to illustrate the invention, the supporting shell 10 and cover shell 12 may be two duplicate stampings. Each shell comprises a back panel 14 corrugated as indicated at 16, for increased stiffness and for reduced thermal contact with the other shell.

At their proximate ends the shells are interconnected by a narrow floating hinge, or bridge, 18 connected to the shell 12 by a pintle 20 and to the shell 10 by a pintle 22. These pintles are parallel, and upon reference to Figure 7 it will be noted that the spacing of the pintles is such that the floating hinge 1.8 is held straight in Figure 7 and keeps the shells 10 and 12 in alignment. Similarly, in the positon of Figures 1 and 2, the plate 18 functions in the same way except that the shells are face to face instead of back to back.

Housed in the supporting shell 1'8 is the heating unit proper. This comprises a flat circular ceramic plate 24 having a sinuous groove 26 for housing a conventional resistance wire 28. The groove has only two ends best indicated at 30 and 32 in Figure 3, and at those ends the wire is suitably aflixed, as by soldering, to terminals 34 and 36 which project down below the plate 24 as indicated in Figure 4, for connection to conductors 38 and 40. It will be noted on reference to Figure 4 that these terminals project toward the back panel 14 of the supporting shell, and that a small insulating plate 42 is affixed to the inner face of the back panel 14 to provide electrical insulation.

The mechanical support for the plate 24 is a bezel comprising a plateau 44 having a circular inner lip 46 extending down and fitting the outer periphery of the plate 24. At the bottom of the lip 46 I provide a peripheral flange 48 turned in to underlie the edge of the plate 24, and a central bridge 50. This leaves two moonshaped openings where the undersurface of the plate 24 is not covered by the bezel. The flange 48 is cut away at 49 (See Figure 5) to provide insulation clearance around the terminal of conductor 40.

The plate 24 is set in place and suitably affixed as by means of a bolt 52 and nut 54 engaging the bridge 50. For convenience in quick assembly, I provide an embossed registry button 56 in the bridge 50, and a co-opcrating socket 58 in the plate 24. The plateau 44 may be stiffened and ornamented by tapered corrugations 60 extending radially out from the lip The outer periphery of the plate 44 is approximately square, except for a slight taper, and is stiffened by a downwardly extending peripheral lip 62. The entirety of the heating unit is simply set in place in the shell 10 and suitably fastened there as by means of fastening screws 64 and 66 passing through aligned apertures in the peripheral lip 62 and the adjacent lip 68 of the shell 10.

The shell 12 has a duplicate peripheral lip 70, and it will be obvious that a single set of dies can stamp both shells 10 and 12.

Both shells project beyond the heating unit, and the projecting portions are apertured to provide a hand-hold opening 72. In closed position this opening is a continuous tube with its opposite ends gently rounded at 74, and large enough so that a human hand of ordinary size can easily engage it with four fingers passing through the hole.

Connection to the power source is secured by merging conductors 38 and 49 in a single cable 76, which is con ventionally knotted at 78 and then drawn through an insulating bushing 86 fastened in the lip 62. The cable issuing from the bushing 89 is then wrapped several times around the tubular metal flange 82 defining that portion of the hand-hold opening 72 that lies in the shell 10. A pair of clips 84 are convenient for keeping the Wrapped cable from falling out of its storage space. The remote end of the cable is a conventic pronged terminal 86, and it is convenient to complete the storage of the cable by shoving the prongs of the fitting 86 through registering apertures in the lip 62.

To improve cooling and ventilation, both in the positions of Figures 1 and 2 and in the position of Figure 6, each shell is provided with six air vents 88 spaced along the peripheral lips 68 and 70.

The heater lends itself readily to a Wide variety of uses.

For transportation and storage it is kept in the condition illustrated in Figures 1 and 2. In this position residual heat due to recent rise is easily dissipated through the vents 38, and the entire device, including the supply cable, is a compact unit.

The first condition of use is illustrated in Figures 3 and 6. When-the supporting surface or foundation on which the heater is positioned is the ground or any other foundation that does not need to be protected from heat, the shells are simply opened and laid in the position of Figure 6, and the culinary art be exercized with the heating unit for the actual cooking and the shell 12 a convenient shallow pan close beside the cooking unit for holding knives, forks, pancake turners, and the like.

The second and, perhaps, the most common conditio of use will be as in Figure 7. This position is obtain able on a moments notice by merely rotating the shell 12 counterclockwise from the position of Figure 6 to bring it around under the shell in this position the shell and its contents are equally accessible to the user, but the device may rest on a table, even on a table covered with oilcloth, and cooking may continue indefinitely Without ever heating the surface of the oilcloth enough to cause it the slightest injury.

This is because the heat originating in the wire 23 travels primarily upward. Also, the plate 24 is a rather powerful thermal insulator, so much so that the ridges between different convolutions of the groove 26 can rise to incandescence while the bottom of the plate remains several hundred degrees cooler. Then the heat must find its way by conduction through the bezel, but the air space between the flanges 46 and 62 is ventilated by the openings 88. Then, that portion of the heat that finally gets into the metal of the shell 1% may be dissipated by air cooling and radiation, and only a fraction of that will pass into the shell 12 because the contact areas between the two shells approach the minimum needed for firm mechanical support, and thus constitute a thermal path of low capacity. Finally, the trivial remaining increment of heat that gets to the shell 12 must travel from the middle of the back panel all the way to the bottom edge of the peripheral lip 7%, while the entire space inside the shell 12 is ventilated by the openings 38. Tests have demonstrated that' with or without a skilledor metal reflector overlying the plate 24, normal heating can continue indefinitely in a closed space with the air at room temperature, and the supporting surface below the shell 12 will never be heated through the device itself to a temperature sufficient to cause injury to linoleum or to a varnished surface.

Of course, if the user has a hot skillet on the plate 24 and shifts its position abruptly to one side or the other, the hot spot in the bottom of the skillet may radiate enough heat down on one side of the device to cause damage where the supporting table is not protected by the device.

The third common condition of use is with the shell 12 rotated about ninety degrees in either direction from the position of Figure 6. With the shells in either of these two relative positions, the device may be set on a supporting surface in edge contact with the supporting surface, and with both shells lying in approximately vertical planes. This will most commonly be done on the floor, and the delivery of electrical energy will be for heating the air in the room.

It will be noted that the high thermal efiectiveness of the arrangement does not depend on thermal insulation of the ordinary type. Kieselguhr, asbestos wool, glass wool, and many other common thermal insulating materials have high thermal effectiveness, but they are easily damaged by moisture and dirt. A device according to the invention achieves effective thermal protection entirely without the use of any such material, and if the metal parts are of rust-proof metal, it can even be lost overboard from a fishing boat and recovered and dried out again, and be almost as good as new.

Others may readily adapt the invention for use under various conditions of service by employing one or more of the novel features disclosed or equivalents thereof. It will, for instance, be obvious that by making the hot plate 24 thinner or the shells deeper, such a plate can be mounted in each of the shells. This doubles the heating and cooking capacity in the position of Figures 3 and 6, but the shell 12 is no longer available as a receptacle for culinary tools. It also doubles the capacity when the device is set on edge. Use in the position of Figure 7 remains identical because the heating unit does not project beyond the edge of the lip, and the lower heating unit in the position of Figure 7 does no harm by its presence.

As at present advised, with respect to the apparent scope of my invention, I desire to claim the following subject matter:

1. A folding electric heater comprising, in combination: two shallow shells; each shell having a back panel; one shell being a supporting shell and the other a cover shell; a fiat heating unit fastened to said supporting shell in a plane generally parallel to the back panel of said supporting shell; at least one of said shells having a peripheral lip extending toward and engaging the other shell when said cover shell is in closed position covering said heating unit; and hinge means interconnecting said shells; said hinge means including an intermediate floating hinge plate; said plate having two parallel spaced pintle portions; each pintle portion being pivoted to one of said shells; the spacing of said pintle portions being substantially half the displacement, normal to the back panel of said supporting shell, required to transfer said cover shell from covering position engaging the heater side of said supporting shell to a parallel position engaging the outer side of said supporting shell; whereby said cover can be swung from covering position away from said heating unit and around into a parallel position engaging said supporting shell on the side remote from said heating unit to constitute a plinth between said supporting shell and a foundation surface.

2. A folding electric heater according to claim 1 in which said shells, when in closed position, substantially enclose and protect said heating unit.

3. A folding electric heater according to claim 1 in which each shell has a peripheral lip extending toward the other shell when in closed position.

4. A folding electric heater comprising, in combination: two shallow shells; each shell having a back panel; one shell being a supporting shell and the other a cover shell; a flat heating unit fastened to said supporting shell in a plane generally parallel to the back panel of said supporting shell; at least one of said shells having a peripheral lip extending toward and engaging the other shell when said cover shell is in closed position covering said heating unit; and hinge means interconnecting said shells; said hinge means including an intermediate floating hinge plate; said plate having two parallel spaced pintle portions; each pintle portion being pivoted ,to one of said shells; the spacing of said pintle portions being substantially half the displacement, normal to the back panel of said supporting shell, required to transfer said cover shell from covering position engaging the heater side of said supporting shell to a parallel position engaging the outer side of said supporting shell; whereby said cover can be swung from covering position away from said heating unit and around into a parallel, position engaging said supporting shell on the side remote from said heating unit to constitute a plinth between said supporting shell and a foundation surface; said shells, when in closed position, substantially enclosing and protecting said heating unit; each shell having aperipheral lip extending toward the other shell when in closed position; said lips meeting in an intermediate plane when in closed position.

5. A folding electric heater according to claim 4 in which said cover shell is empty.

6. A folding electric heater according to claim 4 in which said lips are of equal height and said shells are duplicates.

7. A folding electric heater according to claim 4 in which said heating unit. lies on both sides of a plane defined by the meeting edge portions of said lips.

8; A folding electric heater according to claim 4 in which at least one of said shells extends away from said hinge beyond the heating unit, and theextending shell portion is apertured toiprovide a hand-hold opening.

9. A folding electric heater according to claim 4 in which each shell has a rounded portion defining the periphery of the hand-hold opening at the end of said opening next the back panel of the shell.

10. A folding electric heater according to claim 8 in which said extending shell has a tubular portion defining the hand-hold opening and extending from the back panel substantially to the plane of the edge of the peripheral lip.

11. A folding electric heater according to the claim 10 in which said tubular portion is spaced from the peripheral lip at he end of said shell to define a channel for storing an electric cord wrapped around said tubular portion.

12. A folding electric heater according to claim 4 in which said heating unit includes an electric and thermal insulator having a sinuous groove in one face; an electric resistance housed in said groove; and a bezel; said bezel having a central pocket shaped to house said insulator; a plateau surrounding said pocket; said plateau having its inner periphery in conformity with the contour of said insulator and its outer periphery fitting in said shell next said hinge connection; said plateau having an outer peripheral lip afiixed to said shell.

13. A folding electric heater according to claim in which said heating unit is spaced from said tubular portion to define a second channel for storing the return reaches of a cord wound around said tubular portion.

14. A folding electric heater according to claim 4 in which said cover shell has vent holes in its peripheral lip to increase its thermal insulating effectiveness when laying back to back as a plinth for said supporting shell.

15. A folding electric heater according to claim 4 in which said back panels are corrugated, with registering corrugations; whereby surface contact adequate to transmit heat by conduction is minimized when said shells lie back to back.

16. In a device of the class described, in combination: two panels each provided with hinge connecting means along one side; and a connector provided with complementary hinge connecting means along two spaced parallel axes; each panel having opposite faces referred to for identification as the first and second faces; the spacing between said axes being enough to permit said panels to lie in substantially parallel planes with their first faces juxtaposed in a position referred to for identification as closed, or in substantially parallel planes with their second faces juxtaposed in a position referred to for identification as open; whereby, considering either panel as stationary, the other movable panel can be rotated through substantially 360 and simultaneously offset in a direction normal to its initial and final positions by a distance equal to twice the spacing between said axes, to clear the thickness of the stationary panel; each panel having portions on both faces adapted to define a plane parallel to the plane of the panel and adapted for surface abutment with cooperating portions of the other panel when folded there-against, with the panels parallel to each other in either of two positions separated by a relative rotation of 360 degrees; each of said spaced parallel axes lying in a position intermediate the planes of the opposite faces of the associated panel.

17. A combination according to claim 16 in which said connector is a plate with said hinge connecting means disposed along opposite parallel longitudinal edges.

18. A combination according to claim 16 in which at least one of said panels has one concave face; the plane abutment portions of said concave face lying around the periphery of the concavity.

19. A combination according to claim 18 in which the panel opposite said concave face carries a protuberance adapted to enter and be housed in said concavity.

References Cited in the file of this patent UNITED STATES PATENTS 430,401 Perkins June 17, 1890 1,443,036 Panza Jan. 23, 1923 1,498,654 Hauptman June 24, 1924 1,810,305 Tracy et al. June 16, 1931 1,954,235 Becker et al. Apr. 10, 1934 2,029,620 Johnson Feb. 4, 1936 2,148,822 Kolouch Feb. 28, 1939 2,183,866 Hutchens et al Dec. 19, 1939 2,430,582 Reich Nov. 11, 1947 2,523,353 Boester Sept. 26, 1950 2,565,390 Mitnowsky Aug. 21, 1951 

